1. Field of the Invention
The present invention relates to a magnetic field detector in which a magnetic resistance element is used and a method of manufacturing the magnetic field detector.
2. Description of the Related Art
Hall element is conventionally used for the magnetic field detector. It is possible to enhance the accuracy of the magnetic field detector by increasing a ratio of a detection signal to a noise. Therefore, in order to detect the magnetic field with high accuracy, it is desirable to obtain a higher intensity of signal, that is, it is desirable to increase a resistance change ratio that is changed by the magnetic field. From the above viewpoints, the magnetic resistance element, in which Giant Magneto-resistance (GMR) or Tunnel Magneto-resistance (TMR) is used, has been developed.
This magnetic resistance element detects a change in the outside magnetic field as a change in the resistance. However, the resistance of the magnetic resistance element is also changed by the temperature. Therefore, in an environment in which the outside temperature is greatly changed, it is difficult to use the magnetic resistance element as a magnetic sensor. JP-A-2001-345498 discloses a magnetic detector to solve the above problems. The magnetic detector disclosed in JP-A-2001-345498 is composed in such a manner that a tunnel magnetic resistance element, which is magnetically shielded, and a tunnel magnetic resistance element, which is not magnetically shielded, are connected to each other by the bridge connection so that an influence made by the change in the resistance when the temperature is changed can be reduced. The magnetic resistance element, which is not magnetically shielded, is used as a magnetic resistance element for detection, the resistance of which is changed by the outside magnetic field. The tunnel magnetic resistance element, which is magnetically shielded, is used as a magnetic resistance element for reference, the resistance of which is not changed by the outside magnetic field. In this case, the performance of the magnetic resistance element, which is magnetically shielded, and the performance of the magnetic resistance element, which is not magnetically shielded, are the same.